Functional Activation Studies

A major aim of functional mapping studies of the human brain is to monitor the magnitude and spatial distribution of activity associated with brain function. To that extent cranial functional near-infrared spectroscopy (NIRS) has been widely used to investigate the haemodynamic changes which occur in response to functional activation of specific regions of the cerebral cortex. Based on the tight coupling of neuronal activity and oxygen delivery, changes in the concentration of oxygenated (ΔHbO2) and deoxygenated (ΔHHb) haemoglobin as measured by NIRS are quantified and taken as indicators of cortical activation. For many years now we have pioneered the use of NIRS to monitor brain function in neonates, children and adults. Click here for more information.

Adult

Since 2005 we have been investigating the haemodynamic response of prefrontal brain activation during anagram solving and its relationship with systemic changes such us blood pressure and heart rate. For these studies we are using both an optical topography system (Hitachi ETG-100) or dual channel NIRS systems (NIRO 300, NIRO 200). [poster] [poster]

Figure 1. The results above are group summary data during anagram solving and show the haemodynamic response over the frontal cortex, a control area of the brain (motor cortex), blood pressure and scalp flux (or skin blood flow).

Association analysis between the NIRS haemodynamic measurements with the MBP and scalp flux signals show a relatively high correlation coefficient in some subjects in our studies suggesting a global task-related haemodynamic response.

References
[1] Tachtsidis I., Leung T.S., Tisdall M.M., Devendra P., Smith M., Delpy D.T., Elwell C.E. “Investigation of frontal cortex, motor cortex and systemic haemodynamic changes during anagram solving.” Advances in Experimental Medicine and Biology 614, 21-28 (2008). [Detail]
[2] Tachtsidis I., Leung T.S., Devoto L., Delpy D.T., Elwell C.E. “Measurement of frontal lobe functional activation and related systemic effects: a near-infrared spectroscopy investigation.” Advances in Experimental Medicine and Biology 614, 397- 403 (2008).